An axial-flow pump has a stator blade positioned upstream of the impeller, and it provides an angle α1 = 60° to the flow. The radius of the impeller tip is 285 mm, and the hub radius is 135 mm. Determine the required average blade angle at the exit of the impeller if the pump is to deliver 0.57 m3 /s of water with a theoretical head rise of 2.85 m. The rotational speed is 1500 rpm.